Abstract
BackgroundThe root-knot nematode Meloidogyne graminicola has become a serious threat to rice production as a result of the cultivation changes from transplanting to direct seeding. The nematicidal activity of Aspergillus welwitschiae have been investigated in vitro, and the disease control efficacy of the active compound has been evaluated under greenhouse and field conditions.ResultsThe active compound αβ-dehydrocurvularin (αβ-DC), isolated by nematicidal assay-directed fractionation, showed significant nematicidal activity against M. graminicola, with a median lethal concentration (LC50) value of 122.2 μg mL− 1. αβ-DC effectively decreased the attraction of rice roots to nematodes and the infection of nematodes and also suppressed the development of nematodes under greenhouse conditions. Moreover, αβ-DC efficiently reduced the root gall index under field conditions.ConclusionsTo our knowledge, this is the first report to describe the nematicidal activity of αβ-DC against M. graminicola. The results obtained under greenhouse and field conditions provide a basis for developing commercial formulations from αβ-DC to control M. graminicola in the future.
Highlights
The root-knot nematode Meloidogyne graminicola has become a serious threat to rice production as a result of the cultivation changes from transplanting to direct seeding
Identification of αβ-dehydrocurvularin from A. welwitschiae In total, 15.2 g crude filtrates were extracted by CHCl3/ MeOH eluent from fermentations of A. welwitschiae and were purified by column chromatography on silica gel
By comparing the physiochemical properties with those reported previously, the major nematicidal compounds from A. welwitschiae were identified as αβ-dehydrocurvularin, βγ-dehydrocurvularin and 7-oxocurvularin
Summary
The root-knot nematode Meloidogyne graminicola has become a serious threat to rice production as a result of the cultivation changes from transplanting to direct seeding. The root-knot nematode (RKN) Meloidogyne graminicola is considered one of the most devastating pests on rice, especially in southern Africa, America and Southeast Asia [12, 19, 24]. Much research has aimed to identify nematicidal metabolites from antagonistic microorganisms to control RKNs [10, 16, 35]. The identification of antagonists is necessary for the control of RKN and its commercialization
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